/*
 * Copyright 2002 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * usr/src/cmd/cmd-inet/usr.bin/telnet/enc_des.c
 */

/*
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (C) 1998 by the FundsXpress, INC.
 *
 * All rights reserved.
 *
 * Export of this software from the United States of America may require
 * a specific license from the United States Government.  It is the
 * responsibility of any person or organization contemplating export to
 * obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of FundsXpress. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  FundsXpress makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/* based on @(#)enc_des.c       8.1 (Berkeley) 6/4/93 */
/*
 * Copyright (c) 2016 by Delphix. All rights reserved.
 */

#include <krb5.h>
#include <stdio.h>
#include <arpa/telnet.h>

#ifdef  __STDC__
#include <stdlib.h>
#endif

#include "externs.h"

extern  boolean_t encrypt_debug_mode;
extern  krb5_context telnet_context;

#define KEYFLAG_SHIFT   2
#define SHIFT_VAL(a, b) (KEYFLAG_SHIFT*((a)+((b)*2)))

static  struct _fb {
        Block temp_feed;
        int state[2];           /* state for each direction */
        int keyid[2];           /* keyid for each direction */
        int once;
        unsigned char fb_feed[64];
        boolean_t need_start;
        boolean_t validkey;
        struct stinfo {
                Block           str_output;
                Block           str_feed;
                Block           str_iv;
                unsigned char   str_keybytes[DES_BLOCKSIZE];
                krb5_keyblock   str_key;
                int             str_index;
                int             str_flagshift;
        } streams[2];           /* one for encrypt, one for decrypt */
} des_cfb;

static  void cfb64_stream_iv(Block, struct stinfo *);
static  void cfb64_stream_key(Block, struct stinfo *);

static void
ecb_encrypt(struct stinfo *stp, Block in, Block out)
{
        krb5_error_code code;
        krb5_data din;
        krb5_enc_data dout;

        din.length = DES_BLOCKSIZE;
        din.data = (char *)in;

        dout.ciphertext.length = DES_BLOCKSIZE;
        dout.ciphertext.data = (char *)out;
        /* this is a kerberos enctype, not a telopt enctype */
        dout.enctype = ENCTYPE_UNKNOWN;

        code = krb5_c_encrypt(telnet_context, &stp->str_key, 0, NULL,
                &din, &dout);
        if (code)
                (void) fprintf(stderr, gettext(
                        "Error encrypting stream data (%s)\r\n"), code);
}

void
cfb64_init(void)
{
        register struct _fb *fbp = &des_cfb;

        (void) memset((void *)fbp, 0, sizeof (*fbp));
        fbp->state[0] = des_cfb.state[1] = ENCR_STATE_FAILED;
        fbp->fb_feed[0] = IAC;
        fbp->fb_feed[1] = SB;
        fbp->fb_feed[2] = TELOPT_ENCRYPT;
        fbp->fb_feed[3] = ENCRYPT_IS;

        fbp->fb_feed[4] = TELOPT_ENCTYPE_DES_CFB64;
        fbp->streams[TELNET_DIR_DECRYPT].str_flagshift =
                SHIFT_VAL(0, CFB);
        fbp->streams[TELNET_DIR_ENCRYPT].str_flagshift =
                SHIFT_VAL(1, CFB);
}


/*
 * Returns:
 *      -1: some error.  Negotiation is done, encryption not ready.
 *       0: Successful, initial negotiation all done.
 *       1: successful, negotiation not done yet.
 *       2: Not yet.  Other things (like getting the key from
 *          Kerberos) have to happen before we can continue.
 */
int
cfb64_start(int dir)
{
        struct _fb *fbp = &des_cfb;
        int x;
        unsigned char *p;
        register int state;

        switch (dir) {
        case TELNET_DIR_DECRYPT:
                /*
                 * This is simply a request to have the other side
                 * start output (our input).  The other side will negotiate an
                 * IV so we need not look for it.
                 */
                state = fbp->state[dir];
                if (state == ENCR_STATE_FAILED)
                        state = ENCR_STATE_IN_PROGRESS;
                break;

        case TELNET_DIR_ENCRYPT:
                state = fbp->state[dir];
                if (state == ENCR_STATE_FAILED)
                        state = ENCR_STATE_IN_PROGRESS;
                else if ((state & ENCR_STATE_NO_SEND_IV) == 0)
                        break;

                if (!fbp->validkey) {
                        fbp->need_start = B_TRUE;
                        break;
                }
                state &= ~ENCR_STATE_NO_SEND_IV;
                state |= ENCR_STATE_NO_RECV_IV;
                if (encrypt_debug_mode)
                        (void) printf(gettext("Creating new feed\r\n"));
                /*
                 * Create a random feed and send it over.
                 */
                {
                        krb5_data d;
                        krb5_error_code code;

                        d.data = (char *)fbp->temp_feed;
                        d.length = sizeof (fbp->temp_feed);

                        code = krb5_c_random_make_octets(telnet_context, &d);
                        if (code != 0)
                                return (ENCR_STATE_FAILED);
                }

                p = fbp->fb_feed + 3;
                *p++ = ENCRYPT_IS;
                p++;
                *p++ = FB64_IV;
                for (x = 0; x < sizeof (Block); ++x) {
                        if ((*p++ = fbp->temp_feed[x]) == IAC)
                                *p++ = IAC;
                }
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
                (void) net_write(fbp->fb_feed, p - fbp->fb_feed);
                break;
        default:
                return (ENCR_STATE_FAILED);
        }
        return (fbp->state[dir] = state);
}

/*
 * Returns:
 *      -1: some error.  Negotiation is done, encryption not ready.
 *       0: Successful, initial negotiation all done.
 *       1: successful, negotiation not done yet.
 */
int
cfb64_is(unsigned char *data, int cnt)
{
        unsigned char *p;
        struct _fb *fbp = &des_cfb;
        register int state = fbp->state[TELNET_DIR_DECRYPT];

        if (cnt-- < 1)
                goto failure;

        switch (*data++) {
        case FB64_IV:
                if (cnt != sizeof (Block)) {
                        if (encrypt_debug_mode)
                                (void) printf(gettext(
                                        "CFB64: initial vector failed "
                                        "on size\r\n"));
                        state = ENCR_STATE_FAILED;
                        goto failure;
                }

                if (encrypt_debug_mode)
                        (void) printf(gettext(
                                "CFB64: initial vector received\r\n"));

                if (encrypt_debug_mode)
                        (void) printf(gettext(
                                "Initializing Decrypt stream\r\n"));

                cfb64_stream_iv((void *)data,
                        &fbp->streams[TELNET_DIR_DECRYPT]);

                p = fbp->fb_feed + 3;
                *p++ = ENCRYPT_REPLY;
                p++;
                *p++ = FB64_IV_OK;
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
                (void) net_write(fbp->fb_feed, p - fbp->fb_feed);

                state = fbp->state[TELNET_DIR_DECRYPT] = ENCR_STATE_IN_PROGRESS;
                break;

        default:
                if (encrypt_debug_mode) {
                        (void) printf(gettext(
                                "Unknown option type: %d\r\n"), *(data-1));
                        printd(data, cnt);
                        (void) printf("\r\n");
                }
                /* FALL THROUGH */
        failure:
                /*
                 * We failed.  Send an FB64_IV_BAD option
                 * to the other side so it will know that
                 * things failed.
                 */
                p = fbp->fb_feed + 3;
                *p++ = ENCRYPT_REPLY;
                p++;
                *p++ = FB64_IV_BAD;
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
                (void) net_write(fbp->fb_feed, p - fbp->fb_feed);

                break;
        }
        return (fbp->state[TELNET_DIR_DECRYPT] = state);
}

/*
 * Returns:
 *      -1: some error.  Negotiation is done, encryption not ready.
 *       0: Successful, initial negotiation all done.
 *       1: successful, negotiation not done yet.
 */
int
cfb64_reply(unsigned char *data, int cnt)
{
        struct _fb *fbp = &des_cfb;
        register int state = fbp->state[TELNET_DIR_ENCRYPT];

        if (cnt-- < 1)
                goto failure;

        switch (*data++) {
        case FB64_IV_OK:
                cfb64_stream_iv(fbp->temp_feed,
                        &fbp->streams[TELNET_DIR_ENCRYPT]);
                if (state == ENCR_STATE_FAILED)
                        state = ENCR_STATE_IN_PROGRESS;
                state &= ~ENCR_STATE_NO_RECV_IV;
                encrypt_send_keyid(TELNET_DIR_ENCRYPT,
                        (unsigned char *)"\0", 1, 1);
                break;

        case FB64_IV_BAD:
                (void) memset(fbp->temp_feed, 0, sizeof (Block));
                cfb64_stream_iv(fbp->temp_feed,
                        &fbp->streams[TELNET_DIR_ENCRYPT]);
                state = ENCR_STATE_FAILED;
                break;

        default:
                if (encrypt_debug_mode) {
                        (void) printf(gettext(
                                "Unknown option type: %d\r\n"), data[-1]);
                        printd(data, cnt);
                        (void) printf("\r\n");
                }
                /* FALL THROUGH */
        failure:
                state = ENCR_STATE_FAILED;
                break;
        }
        return (fbp->state[TELNET_DIR_ENCRYPT] = state);
}

void
cfb64_session(Session_Key *key)
{
        struct _fb *fbp = &des_cfb;

        if (!key || key->type != SK_DES) {
                if (encrypt_debug_mode)
                    (void) printf(gettext(
                        "Can't set DES's session key (%d != %d)\r\n"),
                        key ? key->type : -1, SK_DES);
                return;
        }

        fbp->validkey = B_TRUE;

        cfb64_stream_key(key->data, &fbp->streams[TELNET_DIR_ENCRYPT]);
        cfb64_stream_key(key->data, &fbp->streams[TELNET_DIR_DECRYPT]);

        /*
         * Now look to see if cfb64_start() was was waiting for
         * the key to show up.  If so, go ahead an call it now
         * that we have the key.
         */
        if (fbp->need_start) {
                fbp->need_start = B_FALSE;
                (void) cfb64_start(TELNET_DIR_ENCRYPT);
        }
}

/*
 * We only accept a keyid of 0.  If we get a keyid of
 * 0, then mark the state as SUCCESS.
 */
int
cfb64_keyid(dir, kp, lenp)
        int dir, *lenp;
        unsigned char *kp;
{
        struct _fb *fbp = &des_cfb;
        register int state = fbp->state[dir];

        if (*lenp != 1 || (*kp != '\0')) {
                *lenp = 0;
                return (state);
        }

        if (state == ENCR_STATE_FAILED)
                state = ENCR_STATE_IN_PROGRESS;

        state &= ~ENCR_STATE_NO_KEYID;

        return (fbp->state[dir] = state);
}

/*
 * Print ENCRYPT suboptions to NetTrace when "set opt" is used
 */
void
cfb64_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
{
        char lbuf[ENCR_LBUF_BUFSIZ];
        register int i;
        char *cp;
        unsigned char type[] = "CFB64";

        buf[buflen-1] = '\0';           /* make sure it's NULL terminated */
        buflen -= 1;

        switch (data[2]) {
        case FB64_IV:
                (void) snprintf(lbuf, ENCR_LBUF_BUFSIZ, "%s_IV", type);
                cp = lbuf;
                goto common;

        case FB64_IV_OK:
                (void) snprintf(lbuf, ENCR_LBUF_BUFSIZ, "%s_IV_OK", type);
                cp = lbuf;
                goto common;

        case FB64_IV_BAD:
                (void) snprintf(lbuf, ENCR_LBUF_BUFSIZ, "%s_IV_BAD", type);
                cp = lbuf;
                goto common;

        default:
                (void) snprintf(lbuf, ENCR_LBUF_BUFSIZ, " %d (unknown)",
                        data[2]);
                cp = lbuf;
        common:
                for (; (buflen > 0) && (*buf = *cp++); buf++)
                        buflen--;
                for (i = 3; i < cnt; i++) {
                        (void) snprintf(lbuf, ENCR_LBUF_BUFSIZ, " %d", data[i]);
                        for (cp = lbuf; (buflen > 0) && (*buf = *cp++); buf++)
                                buflen--;
                }
                break;
        }
}


static void
cfb64_stream_iv(Block seed, register struct stinfo *stp)
{
        (void) memcpy((void *)stp->str_iv,      (void *)seed, sizeof (Block));
        (void) memcpy((void *)stp->str_output,  (void *)seed, sizeof (Block));

        stp->str_index = sizeof (Block);
}

void
cfb64_stream_key(Block key, register struct stinfo *stp)
{
        (void) memcpy((void *)stp->str_keybytes, (void *)key, sizeof (Block));
        stp->str_key.length = DES_BLOCKSIZE;
        stp->str_key.contents = stp->str_keybytes;
        /*
         * the original version of this code uses des ecb mode, but
         * it only ever does one block at a time.  cbc with a zero iv
         * is identical
         */
        /* this is a kerberos enctype, not a telopt enctype */
        stp->str_key.enctype = ENCTYPE_DES_CBC_RAW;

        (void) memcpy((void *)stp->str_output, (void *)stp->str_iv,
            sizeof (Block));

        stp->str_index = sizeof (Block);
}

/*
 * DES 64 bit Cipher Feedback
 *
 *     key --->+-----+
 *          +->| DES |--+
 *          |  +-----+  |
 *          |           v
 *  INPUT --(--------->(+)+---> DATA
 *          |             |
 *          +-------------+
 *
 *
 * Given:
 *      iV: Initial vector, 64 bits (8 bytes) long.
 *      Dn: the nth chunk of 64 bits (8 bytes) of data to encrypt (decrypt).
 *      On: the nth chunk of 64 bits (8 bytes) of encrypted (decrypted) output.
 *
 *      V0 = DES(iV, key)
 *      On = Dn ^ Vn
 *      V(n+1) = DES(On, key)
 */

void
cfb64_encrypt(register unsigned char *s, int c)
{
        register struct stinfo *stp =
                &des_cfb.streams[TELNET_DIR_ENCRYPT];
        register int index;

        index = stp->str_index;
        while (c-- > 0) {
                if (index == sizeof (Block)) {
                        Block b;
                        ecb_encrypt(stp, stp->str_output, b);
                        (void) memcpy((void *)stp->str_feed, (void *)b,
                                sizeof (Block));
                        index = 0;
                }

                /* On encryption, we store (feed ^ data) which is cypher */
                *s = stp->str_output[index] = (stp->str_feed[index] ^ *s);
                s++;
                index++;
        }
        stp->str_index = index;
}

int
cfb64_decrypt(int data)
{
        register struct stinfo *stp =
                &des_cfb.streams[TELNET_DIR_DECRYPT];
        int index;

        if (data == -1) {
                /*
                 * Back up one byte.  It is assumed that we will
                 * never back up more than one byte.  If we do, this
                 * may or may not work.
                 */
                if (stp->str_index)
                        --stp->str_index;
                return (0);
        }

        index = stp->str_index++;
        if (index == sizeof (Block)) {
                Block b;
                ecb_encrypt(stp, stp->str_output, b);
                (void) memcpy((void *)stp->str_feed, (void *)b, sizeof (Block));
                stp->str_index = 1;     /* Next time will be 1 */
                index = 0;              /* But now use 0 */
        }

        /* On decryption we store (data) which is cypher. */
        stp->str_output[index] = data;
        return (data ^ stp->str_feed[index]);
}